Bicycle-back bone



( o Model.) 4

T. B. JEPPERY' BICYCLE BAOKBONE.

Patented Mar. 22, 1887.

with M111 1 @VuwmduQJ/M. JQMW k/i ri gx ,through D b, Fig. 1.

UNITED STATES PATENT OFFICE.

THOMAS B. JEFFERY, OF CHICAGO, ILLINOIS.

BlCYCLE-BACKBONE.

SPECIFICATION forming part of Letters Patent No. 359,608, dated March 22, 1887.

Application filed August 23, 1886. Serial No. 211,603.

To all whom it may concern:

Be it known that I, THOMAS B. JEFFERY, a citizen of the'United States, residing at Ohicago, in the county of Cook and State of Illinois, have invented certain new I and useful Improvements in Bicycle-Backbones, which are fully described and set forth in the following specification, reference being had to the accompanying drawings, forming'a part thereof.

Figure 1 is a side elevation of the neckpiece, showing the position of the seat and of the drive-wheel in dotted line. Fig. 2 is a rear elevation of the same. Fig. 3 is a plan of the same. Fig. 4 is a rear elevationof the rear portion of the backbone, including the fork, the forward part being broken away. Fig. 5 is a side elevation of the same, one branch of the fork being broken away. Fig. 6 is a rear elevation of the rear fork at one stage in the process of its manufacture. Fig. 7 is a section Fig. 8 is a section of the backbone slightly modified from the form shown at Fig. 7, but taken at substantially the same point as Fig. 7.

A is the head-piece, which is in the usual form, except that the rear portion, A, onto which the backbone is j oinedusually by brazing-is made hollow, and to compensate for the diminution of strength is extended rearwardly on the lower side in the tongue A giving it greater surface for brazing to the backbone, and affording strength at the point where the strain is most severe. When this part is made solid it is practically absolutely rigid, and its inelasticity causes the strain to be concentrated upon the tubular backbone at the end of this solid part, so that the backbone is especially liable to break at that point whensubjected to severe strain. When, however, this part is made tubular-,itis absolutely rigid only where it joins the stem A", and by tapering it out at the rear in the tongue A and securing thetubular backbone outside of it thestiffness of the structure is gradually increased toward the stem,and the strain is thereby distributed, instead of being concentrated at one point.

B is the backbone. O is the saddle. D is the drive-wheel.

In order that the distance from the saddle to the axle (and hence to the pedals) may be shortened without diminishing the diameter of the wheel or weakening the parts materially,

(No model.)

I compress vertically that portion of the back bone between the saddle and the wheel-via,

the part in the rear of the dottedlineb b. The form thereby given to the cross-section may be elliptical, as in Fig. 7, or preferably, on some accounts, approximately D-shaped, with the more convex curve uppermost. In either of the flattened forms the vertical elasticity is somewhat greater than when strictly circular. This vertical compression maybe continuedto the extreme forward end, and in that case the rear portion, A, of the neck-piece is necessarily similarly. compressed to receive the backbone and joined thereto, as shown.

B B is the rear fork. It has heretofore been customary to make the rear fork in a separate piece and join it by brazing or riveting onto the backbone. I avoid the expense of making this junction and increasethe strength of the structure by making the backbone and fork of one piece of tubular metal, the tube being curved over the drive-wheel, as usual. It is by suitable devices compressed longitudinally and expanded transversely at a point, I), just above the fork. The longitudinal compression furnishes metal for the transverse expansion, and I prefer to compress longitudinally enough to increasethe thickness at the expanded part beyond what it was before expansion, so that the strength and stiffness at that part shallbe proportionateto the strain to which it is subjected. The expanded portion is medially cut away or rifted alittle distance below or rearward from the point I), and the lateral portions B B are somewhat farther spread apart, and thus form the fork. Each lateral portion B is thus left concavo-convex in cross-section, andthey are afterward drawn tapering, and at the rear lower extremities are flattened to form the eyes If D which receive the axle of the rear wheel.

I claim- 1. A bicycle-backbone and rear fork made in one piece, the backbone being tubular and mediallyrifted in the plane of the curvatureto form the fork, and thickened at the vicinity of the rift, substantially as set forth.

2. A bicycle-backbone and rear fork made of asingle piece of tubing expanded at b and rifted beyond such expanded portion, and the two branches laterally separated to form the rear fork, substantially as set forth.

IOC

3. Abicycle-baekbone and rear fork made 5. A bicycle-backbone made tubular, havof a single piece of tubing expanded transing its vertical diameter less than its horizonversely and thickened at b, and rifted beyond tal diameter at the upper forward part, subthat point to form the fork to admit the rear stantially as set forth. 15 5 wheel, substantially as set forth. In testimony whereof I have hereunto set my 4-. In combination, substantially as set forth, hand, in the presence of two witnesses, this the neck-pieee A, having the rearwardly-ex- I 17th day of August, A. D. 1886.

tended part A, made tubular and prolonged THOS. B. JEFFERY. at the lower side in the tongue A and the lVitnesses:

Io tubular backbone lapping said tubular part CHAS. S. NEEROS, A and tongue A and secured thereto. V. T. DAWSON. 

